The present invention concerns a procedure for comparing a reception beam impinging on a laser receiver with a rotating laser beam and a device for performing such a procedure.
Rotating lasers are used internally and externally for leveling and marking tasks, such as the display of laser markings running horizontally, vertically or diagonally on a target area or the determination and review of horizontal height profile, vertical lines, vanishing lines and perpendicular points. Rotating lasers can be arranged in various device positions which are formed as a horizontal and vertical position. Here, rotating lasers which can be used horizontally and which are used exclusively in horizontal position are distinguished from rotating lasers that can be used horizontally and vertically which are used in horizontal and vertical position.
In the case of rotating lasers which may be used without protective measures, such as goggles, the maximum laser power is limited. The permitted maximum laser powers often lead, in the case of leveling and marking tasks externally, to laser beams which are not visible or only poorly visible. To improve the visibility of the laser beams, target systems or laser receivers are held into the laser beam. Laser receivers are held as a manual device directly in the laser beam by an operator or fastened to a telescopic or leveling arm. Known laser receivers include an evaluation unit and at least one detection field with a longitudinal and a transverse direction, whereby the laser receiver is aligned depending on the device position of the rotating laser in a longitudinal or transverse arrangement.
In the case of leveling and marking tasks, incorrect measurements can result from foreign beams of reflections from the rotating laser beam. Various procedures are known for comparing a reception beam hitting a laser receiver with the rotating laser beam. To reduce the risk of incorrect measurements with a laser receiver, it is known how to modulate the rotating laser beam of the rotating laser with a modulation signal. The reception beam impinging on the laser receiver is evaluated by the evaluation unit of the laser receiver and classified as a rotating laser beam if the reception beam was modulated with the modulation signal. What is disadvantageous is that a reflection from the rotating laser beam on a reflecting area is not detected by the evaluation unit. The reflected laser beam was modulated with a modulation signal and is classified by the evaluation unit of the laser receiver as a rotating laser beam.
U.S. Pat. No. 7,119,316 B2 reveals another known procedure for comparing a reception beam hitting a laser receiver with a rotating laser beam, which is emitted by a rotating laser. The laser receiver includes a detection field that is composed in a longitudinal direction of several photodetector arrays, whereby the photodetector arrays each include several photodetectors in a longitudinal direction. When a reception beam impinges on the detection field, a first and second reference signal is determined by the evaluation unit for each photodetector array, whereby the first and second reference signal represent the amplitudes of the outer photodetectors of the photodetector array which are covered by the reception beam. The reference signals are further processed by the evaluation unit through summation, differentiation and division, until a quotient results for the evaluation. This quotient is compared with a predefined limit value. If the quotient is less than the limit value, the reception beam is classified as a laser beam (“moving thin beam of laser light”). If the quotient is greater than the limit value, the reception beam is classified as a foreign beam (“omni-directional pulse of light”).
From U.S. Pat. No. 7,224,473 B2, another procedure for comparing a reception beam impinging on a laser receiver with a rotating laser beam is known. The laser receiver includes a detection field which is composed of several photodetectors in a longitudinal direction, and an additional photodetector. When a reception beam impinges on the laser receiver, the evaluation unit determines a first, second and third reference signal, whereby the first reference signal represents the electrical output of a first outer photodetector which is covered by the reception beam, the second reference signal represents the electrical output of a second outer photodetector which is covered by the reception beam and the third reference signal represents the electrical output of the additional photodetector. Using the third reference signal, an evaluation of the reception beam takes place. If the amplitude of the third reference signal is sufficiently low, the reception beam is classified as a laser beam of the rotating laser. If the amplitude of the third reference signal is sufficiently high, on the other hand, the reception beam is classified as a foreign beam (“omni-directional pulse of light”).
The procedures known from U.S. Pat. No. 7,119,316 B2 and U.S. Pat. No. 7,224,473 B2 for comparing a reception beam impinging on a laser receiver with a rotating laser beam from a rotating laser, have the disadvantage that a reflection from the rotating laser beam on a reflecting surface is not detected by the evaluation unit of the laser receiver and is incorrectly classified as a rotating laser beam. Through the reflection of the rotating laser beam on the reflecting surface, the amplitudes of the reference signals do not change or only change insignificantly, and have no influence on criteria for the evaluation of the reception beam.
The task of the present invention consists in the development of a procedure for comparing a reception beam hitting a laser receiver with a rotating laser beam, where the risk of incorrect measurements due to a reflection of the rotating laser beam on a reflecting surface is reduced. Furthermore, the procedure should be suited for a largely automatic execution.
The procedure for comparing a reception beam hitting a laser receiver with a rotating laser beam which is emitted by a rotating laser in a rotating direction around a rotational axis, whereby the laser receiver includes an evaluation unit and at least one detection field with a first measuring range and a second measuring range, exhibits the following steps according to the invention:
when the reception beam impinges on at least one detection field of the laser receiver, a reception signal is determined which realizes the time trend of the reception beam impinging in the first measuring range, and a second reception signal which realizes the time trend of the reception signal impinging in the second measuring range,
a direction of movement of the reception beam relative to the laser receiver is determined from the first and second reception signal, and
the direction of movement of the reception beam is compared by the evaluation unit with the rotational direction of the rotating laser beam.
In the invented procedure for comparing a reception beam with a rotating laser beam, at least one detection field exhibits a first and second measuring range and the evaluation unit of the laser receiver determines a first and second reception signal. The first reception signal represents the time trend of the reception beam hitting in the first measuring range and the second reception signal represents the time trend of the reception beam hitting in the second measuring range. A laser receiver, which exhibits at least one detection field with a first and second measuring range, makes it possible to detect a direction of movement of the reception beam relative to the laser receiver. As part of the invented procedure, the evaluation unit of the laser receiver determines a direction of movement of the reception beam relative to the laser receiver from the first and second reception signal and compares the direction of movement of the reception beam with the direction of rotation of the rotating laser beam.
Using the invented procedure, a reflection from the rotating laser beam on a reflection surface can be detected; foreign beams that do not rotate around an axis of rotation can be distinguished from the rotating laser beam. In the case of a non-rotating foreign beam, the time trend of the first reception signal and the time trend of the second reception signal essentially match and the evaluation unit cannot determine a direction of movement of the reception beam relative to the laser receiver from the first and second reception signal. By comparing the direction of movement of the reception beam and the direction of rotation of the rotating laser beam, a reflection from the rotating laser beam on a reflecting surface can be detected. The rotating laser moves the rotating laser beam in a known direction of rotation around the axis of rotation. When the rotating laser beam impinges on the laser receiver as a reception beam after a reflection on a reflecting surface, the direction of movement of the reception beam is opposed to the known direction of rotation of the rotating laser beam.
The other steps of the invented procedure depend on whether the evaluation unit can determine a direction of movement of the reception beam relative to the laser receiver from the first and second reception signal. Depending on the direction of movement of the reception beam, non-rotating foreign beams and reflected laser beams can be distinguished from the rotating laser beam using the invented procedure.
The reception beam is classified by the evaluation unit as a foreign beam, if the time trend of the first reception signal and the time trend of the second signal essentially match. Any beam is designated a foreign beam that is different from the rotating laser beam of the rotating laser. In the case of a non-rotating foreign beam, the time trend of the first reception signal and the time trend of the second reception signal essentially match, and the evaluation unit cannot determine a direction of movement of the reception beam relative to the laser receiver from the first and second reception signal.
If the time trend of the first reception signal is different from the time trend of the second reception signal, the direction of movement of the reception signal is determined by the evaluation unit. Here, the direction of movement of the reception beam is defined as the direction-to, if the first reception signal begins before the second reception signal and/or ends before the second reception signal, and the direction of movement of the reception signal is defined as the direction-back, if the second reception signal begins before the first reception signal and/or ends before the first reception signal.
The other steps of the invented procedure depend on whether the direction of movement of the reception signal and the direction of rotation of the rotating laser beam are in the same or the opposite direction. The invented procedure distinguishes two variants: in a first variant, the direction of movement of the reception beam and the direction of rotation of the rotating laser beam are in the same direction, and in a second variant, the direction of movement of the reception signal and the direction of rotation of the rotating laser beam are opposed.
When the direction of movement of the reception signal and the direction of rotation of the rotating laser beam are in the same direction, the reception beam is classified as a rotating laser beam by the evaluation unit. The rotating laser moves the rotating laser beam in a known direction of rotation around the axis of rotation. When the rotating laser beam impinges on the laser receiver as reception beam without a reflection on the reflecting surface, the direction of movement of the reception beam is in the same direction as the known direction of rotation of the rotating laser beam. In the invented procedure, the reception beam is always classified as rotating laser beam by the evaluation unit when the direction of movement and the direction of rotation are in the same direction.
The direction of movement of the reception beam is also in the same direction as the known direction of rotation in case of an even number of reflections of the rotating laser beam, so that reception beams that arise from an even number of reflections from the rotating laser beam are incorrectly classified as rotating laser beam by the evaluation unit. In the practical application of rotating lasers and laser receivers, the simple reflection of the rotating laser beam on a reflecting surface represents the most common cause of incorrect measurements, so that the invented procedure does reduce the risk of incorrect measurements, but cannot completely prevent incorrect measurements.
Particularly preferred, the laser receiver is switched by the evaluation unit into a measuring mode, whereby in the measuring mode, a position of the reception beam is determined in a longitudinal direction of at least one detection field. When an impinging reception beam is classified by the evaluation unit as rotating laser beam, the laser receiver can be used as intended. For this, the laser receiver can be switched by the evaluation unit into a measuring mode.
When the direction of movement of the reception beam and the direction of rotation of the rotating laser beam are in the opposite direction, the reception beam is classified by the evaluation unit as reflected laser beam. The rotating laser moves the rotating laser beam in a known direction of rotation around an axis of rotation. When the rotating laser beam impinges on the laser receiver as a reception beam after a reflection on a reflecting surface, the direction movement of the reception beam is opposed to the known direction of rotation of the rotating laser beam. In the invented procedure, the reception beam is always classified by the evaluation unit as reflected laser beam, when the direction of movement and the direction of rotation are in the same direction.
The direction of movement of the reception beam is also in the opposite direction of the known direction of rotation in the case of an odd number of reflections from the rotating laser beam, so that reception beams that arise from an odd number of reflections from the rotating laser beam can be correctly classified by the evaluation unit as reflected laser beam.
In the invented procedure, the rotating laser beam is moved in a known direction of rotation around an axis of rotation. The evaluation unit of the laser receiver determines a direction of movement of the laser beam and compares the direction of movement with the direction of rotation of the rotating laser. Here, it is to be observed that the direction of movement depends on the position of the laser receiver and the absolute direction of movement in opposing positions of the laser receiver are in the opposite direction. The position of the laser receiver to the rotating laser can be determined using the rotating laser beam.
In a preferred further development of the procedure, the rotating laser beam is moved by 360 degrees around the axis of rotation and the angle of 360 degrees is subdivided into a first and second angle range, whereby the rotating laser beam distinguishes itself in a beam property or in several beam properties. As part of the invented procedure, the evaluation unit of the laser receiver analyzes the impinging reception beam. Using the beam property in which the rotating laser distinguishes itself in the first and second angle range, the evaluation unit can determine the angle range in which at least one detection field of the laser receiver is hit by the reception beam.
Preferably, the rotating laser beam is modulated with a modulation signal, whereby in the first angle range, a first modulation signal is used and in the second angle range, a second modulation signal is used which is distinct from the first modulation signal. The first and second modulation signal can be different from one another with respect to amplitude, form and/or a modulation frequency. As part of the invented procedure, the evaluation unit of the laser receiver analyzes the impinging reception beam and can determine the modulation signal with which the reception beam was modulated. Using the modulation signal, the evaluation unit can determine the angle range in which at least one detection field of the laser receiver was hit by the reception beam.
According to the invention, a device is provided for the performance of a procedure with a rotating laser which emits a laser beam that rotates in a direction of rotation around an axis of rotation, and a laser receiver which includes an evaluation unit and at least one detection field with a first measuring range and a second measuring range. In a first variant, the rotating laser is aligned in a vertical position and the laser receiver is aligned in a transverse direction. Here, the axis of rotation of the rotating laser and the longitudinal direction of at least one detection field are aligned perpendicular to a direction of gravitation of the gravitational field, and the transverse direction of at least one detection field is aligned parallel to the direction of gravitation. In a second variant, the rotating laser is aligned in a horizontal position and the laser receiver in a longitudinal arrangement. Here, the axis of rotation of the rotating laser and the longitudinal direction of at least one detection field is aligned parallel to the direction of gravitation and the transverse direction of at least one detection field is aligned perpendicular to the direction of gravitation.
Preferably, the laser receiver includes a first detection field and a second detection field spaced at a distance from it, whereby the first detection field exhibits the first measuring range and the second detection field exhibits the second measuring range.
Particularly preferred, the laser receiver exhibits an inclination sensor which measures an inclination of the laser receiver relative to a direction of gravitation of the gravitational field. The inclination sensor can be used to clearly define the alignment of the laser receiver. In the embodiment of the invented procedure, the laser receiver is aligned in longitudinal or in transverse arrangement, whereby the longitudinal or transverse arrangement of the detection field should run parallel to and the transverse direction of the detection field should run perpendicular to the vertical. The longitudinal or transverse direction of the detection field and the direction of gravitation can be in the same direction or in opposed directions. Using the inclination sensor, both of the alignments can be distinguished from one another as “in the same direction” or “in the opposite direction”.
Particularly preferred, the rotating laser and the laser receiver are able to be connected by way of a communication connection, whereby the communication occurs between the evaluation unit of the laser receiver and a control unit of the rotating laser. In the embodiment of the invented procedure, the evaluation unit of the laser receiver determines a direction of movement of the reception beam relative to the laser receiver from the first and second reception signal and compares the direction of movement of the reception beam with the direction of rotation of the rotating laser beam. The direction of rotation of the rotating laser beam can be transmitted by the rotating laser to the evaluation unit by way of the communication connection, such that the invented procedure can be performed automatically.
Embodiment examples of the invention are described in the following using the drawings. The drawings are not necessarily meant to represent the embodiment example to scale, rather the drawings, where helping to explain, are designed schematically and/or slightly distorted. Here, it is to be taken into account that various modifications and changes concerning the form and the details of an embodiment example can be performed, without deviating from the general idea of the invention. The general idea of the invention is not limited to the exact form or the details of the embodiment example shown and described or limited to an object that would be limited in comparison to the object claimed in the claims. In the given dimension ranges, values that also are within the named limits are revealed and can be used and claimed as desired.
For the sake of simplicity, the same reference signs are used in the following for identical or similar parts or parts with identical or similar function.